1. Field of the Invention
This invention relates generally to packages of electronic components that require cooling and, more particularly, to electronic component packages that are sealed and have a cooling fluid enclosed therein.
2. Description of the Related Art
As the density of electronic elements in electronic components has increased, the removal of heat from the components has become increasingly important to prevent compromise of the operating characteristics of the elements as a result of temperature increase.
In order to remove the heat form the components, it is known to cause a flow of air over the components. However, the use of flowing gas as a cooling medium has been found to be unsatisfactory as the density of elements in the electronic components has increased. To overcome the problems arising because of the relatively low heat capacity of a gas, a flowing liquid has been utilized. The flowing liquid indeed provides a satisfactory cooling of the high density components at the cost of elaborate apparatus for circulating the liquid past the components. The added complexity of the circulation apparatus has limited the application of this technique to expressive data processing systems.
Another method of cooling electronic components having a high electronic element density is by placing a cooling plate, a structure with a high thermal conductivity for conducting heat away from the from the component, in contact with the components, i.e. of a circuit board. The difficulty in matching the contours of the components to the contours of the cooling plate and the problems involved in maintaining good thermal contact though a range of temperatures has limited the usefulness of this cooling technique. However, if the components the cooling plate are not in contact, but a liquid with good thermal conductivity is interposed between the components and the cooling plate, the cooling of the components can be accomplished without the problems associated with other techniques. In addition, practical considerations have caused the cooling fluid to be enclosed. This enclosure has provided an addition source of problems. As the temperature of the cooling fluid is changed, the volume of the cooling fluid can change resulting in unacceptable stresses being developed in the enclosure.
A need has therefore been felt for apparatus and method for compensating for the cooling fluid volume changes while minimizing the additional complexity resulting from the compensation technique.